The role of surface charge in ionic germination of Clostridium perfringens spores

The surface charge against pH behaviour of spores of Clostridium perfringens type A was determined using a colloid titration method in the pH range 4-9. The native spores as well as various ionic forms of the spores loaded with divalent cations were found to be negatively charged. A positive colloid, MGCh, inhibited the ionic germination of the spores and this inhibition was highly dependent on pH. However, another positive colloid, GCh, did not inhibit the germination. Chemical modification of carboxyl groups on the spore surface by use of a water-soluble carbodiimide with two nucleophiles, glycine ethyl ester and taurine, caused spores not only to have little or no colloidal charge but also to lose the ability to germinate. The modification of carboxyl groups in the spore coat protein also resulted in elimination of, or marked reduction in its negative charge. These results suggest that carboxyl groups in the spore coat protein are the major negatively charged species on the spore surface. The role of surface charge in the ionic germination of the spores is discussed.